Sandwich-like heterojunction of NiO-Ni-TiO2 for simultaneous production of hydrogen and value-added products from glycerol photoreforming

Abstract

Achieving sustainable solar energy conversion and storage can be achieved using an alternative approach, namely photocatalytic hydrogen generation. However, the heightened cost of producing green hydrogen is attributed to the nonselective oxidation of sacrificial agents. In this work, a strategic design of a bifunctional photocatalyst that can concurrently produce hydrogen and generate value-added compounds from glycerol is demonstrated. A p-n heterojunction photocatalyst is firstly fabricated by loading NiO nanoparticles onto TiO₂ with different morphologies to examine their effect on hydrogen production performance and glycerol conversion. Then, sandwich-like heterojunction of NiO-Ni-TiO₂ was synthesized by in-situ thermal treatment of NiO-TiO₂ p-n junction. The formation of a collaborative Schottky and p-n (SPN) heterojunction significantly enhances charge separation efficiency, thereby, boosting the activity of glycerol photoreforming to produce hydrogen together with valuable chemicals. By optimizing the morphology and Ni-NiO ratio, approximately 24500 µmolh⁻¹g⁻¹ of hydrogen was delivered together with 58 % of glycerol conversion into dihydroxyacetone and glyceraldehyde. This present work demonstrates a notable illustration of the rational design of bifunctional photocatalyst for solar-driven coproduction of hydrogen and value-added chemicals.